Cooling towers are used in many applications. For example, air conditioning systems for large buildings employ cooling towers for carrying out a portion of the heat exchange that is essential to the cooling process. Industrial processes, such as chemical production, metals production, plastics production, food processing, etc., generate heat that must be disposed of, often by the use of cooling towers. The cooling tower is a housing that channelizes air in proximity to a heat exchange liquid, for example, water. A heat exchange fluid may be circulated through the cooling tower and at least one fan may be mounted on the cooling tower to produce a flow of cooling air in proximity to the heat exchange liquid. Heat is transferred from the heat exchange fluid to the air, largely through the evaporation of a small percentage of fluid which substantially lowers the temperature of the primary heat exchange fluid. The cooled heat exchange fluid can then return to the industrial process to perform a heat exchange function for either industrial processes or commercial air conditioning systems.
Conventional cross-flow cooling towers are presently in widespread use in such areas as factory complexes, chemical processing plants, hospitals, apartment and/or condominium complexes, warehouses and electric generating stations. Conventional cross-flow cooling towers are constructed with upright unitary or sectionalized fill structures surmounted by hot water distribution basins and cold water collection basins. The hot water basins are usually equipped with target nozzles or other hot water distributors which distribute the incoming water over the fill. The interior space bounded by the fill structures and the cold water basins define the plenum for the tower. A fan assembly made up of an apertured horizontal deck, which supports an upright, venturi-shaped stack, is positioned at the upper opening of the water cooling tower. This configuration provides a plenum large enough to enable a smooth transition of the flow gas from the generally horizontal direction, through the fill assembly, to the generally vertical direction, and out the exhaust port of the tower assembly. In the operation of the cross-flow cooling towers, hot water is introduced at the top of the fill while the air is introduced along the upright sides of the tower. As the water descends in an even distribution along the fill section, the cooling cross-flow air currents intersect the descending water in a heat exchanging relation. Subsequently, the cooled water is collected in a water basin below while the hot, moist air is discharged into the atmosphere.
In a cross-flow cooling tower, there is no necessity for the air to make radical changes of direction into the fill and the air inlet is spaced along the entire height of the fill. Therefore, the overall air pressure losses in the fill are usually less than those of a conventional counter-flow tower resulting in the passing of air through the tower more easily.
Conventional cross-flow cooling towers generally employ various varieties of splash-type fill sections consisting of elongated bars of a specific configuration for dispersing the descending released water. More recently, film type fill sections have been developed which have proven substantially more efficient than splash fill sections. These typically corrugated film fills generally consist of a series of thin, opposed sheets formed of synthetic resin materials in which water passes along the sheets of “film”.
The highest potential for cooling exists at the top of the air inlet sides where the hottest water comes into contact with the coldest air. Once such air has been heated such that the wet bulb temperature of the air is near the water temperature, the air has no more capacity to cool the water, and such heat saturated air prevents the introduction of cooler ambient air into the fill. Air near the top of the tower typically experiences this condition because it initially contacts the hottest water, and all other water along its path of travel is about the same temperature. Air entering near the bottom of the tower initially is exposed to water that has been significantly cooled. As it traverses through the fill, the temperature of the water encountered by the bottom air currents rises, which allows the air to take on more heat.
The hot water basins in a cross-flow tower are normally constructed to serve as an air seal to prevent air entering the tower through the top of the fill. Additionally, air seals along the length of the tower are provided along the inboard and outboard edges of the basins to seal from the bottom of the basins to the top of the fill. These seals prevent air from entering the spray chamber and bypassing the fill structure. Sealing of the distribution basins also minimizes the contact between incoming air currents and relatively large water particles adjacent the spray nozzles or water distributors.
Presently, a majority of unitary cooling towers are assembled from a plurality of pieces of sheet metal that are mounted to a metallic support frame. Unitary cooling towers typically are manufactured at a location remote from the installation site. The towers are then shipped to the installation site in a substantially assembled form. Due to the metallic materials with which the cooling towers are assembled, the towers are fairly heavy and therefore require extensive structural support. In addition, the cost of present cooling towers are also adversely affected by the labor intensive processes for manufacturing and assembling the various metallic components of the cooling towers.
Metallic cooling towers are also subject to corrosion and/or rust. Thus, the metallic towers have a relatively short operational life. Corrosion and/or rust problems can be deterred by employing corrosion and/or rust resistant alloys. However, these metallic materials significantly increase the manufacturing cost of the water cooling tower. Alternatively, plastics such as polyethylene are well known for being moldable into prescribed form and function and are utilized in the art. However, polyethylene material properties are relatively weak and flexible. To compensate for these properties in monolithic parts, designers must use large quantities of polyethylene to create bigger, thicker and deeper sections to minimize stresses and deflections.
Accordingly, it is desirable to provide a cooling tower design that offers a substantial reduction in parts, avoiding complex and costly assembly of components. It is also desirable to manufacture a water cooling tower that is light in weight, durable and resists corrosion.